monkeydelmagico
Diamond Member
- Nov 16, 2011
- 3,961
- 145
- 106
Ethanol should work fine to then. YaY! this project is looking GOOD. :biggrin:
Ethanol should work fine to then. YaY! this project is looking GOOD. :biggrin:
You cut that heatsink in the wrong place if your going to replace the fluid.And the amount of fluid is critical,Cut the top of the heatpipes and put the heatsink in boiling water so the heatpipes are above the water.Add your methanol or whatever you want to use and seal the pipes while it's still in the water.when the pipes cool it'll create a good vacuum.If you're going to use the heatsink upright you don't have to worry about wicks so you can make them out of regular copper tubing
The Boston Dangler
Lifer
- Mar 10, 2005
- 14,647
- 2
- 0
i change the fluid in my heatpipes regularly :whiste:
you guys are yahoos, now stop spreading misinformation. it's not magic - it's mathematics. heatpipes are real, they really are in computers, and they really work.
you guys are yahoos, now stop spreading misinformation. it's not magic - it's mathematics. heatpipes are real, they really are in computers, and they really work.
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There is no liquid in pipe-shaped heatsinks that cooler manufacturers call "heat pipes." Sorry to burst your bubble on that. And there are a very few obvious reasons why:
1. If the "working liquid" is water, then water becomes liquid at atmospheric pressure, which is approx. 14 psi at sea level.
2. If the working liquid is not water, and evaporates at atmospheric pressure, this is called a "refrigerant" and would have to be LABELED clearly on the box, since refrigerants can be flammable and/or toxic.
If you still disagree, you obviously know more than I do. I will admit that you know more than I do, but only IF you answer this question directly and clearly:
If a cpu with "heat pipes" is indeed a two-phase change cooler, how and where do they apply vacuum to the pipes?
If you answer that, I will admit you're right.
1. If the "working liquid" is water, then water becomes liquid at atmospheric pressure, which is approx. 14 psi at sea level.
2. If the working liquid is not water, and evaporates at atmospheric pressure, this is called a "refrigerant" and would have to be LABELED clearly on the box, since refrigerants can be flammable and/or toxic.
If you still disagree, you obviously know more than I do. I will admit that you know more than I do, but only IF you answer this question directly and clearly:
If a cpu with "heat pipes" is indeed a two-phase change cooler, how and where do they apply vacuum to the pipes?
If you answer that, I will admit you're right.
heatpipes have water in them,water boils at 75-80f in a vacuum.You heat the pipe to force the air out,seal it and when it cools it creates a vacuum
Nice try, but if you heat the water enough the steam will escape along with the air. Would require a valve to charge under vacuum, in fact.
The last link I posted in my above post describes how all air is removed and vacuum is applied in a phase change cooler.
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That would not create sufficient vacuum. Do you know the amount of vacuum that must be applied in order for water to boil at 70 degrees Celsius?
Heating water to below boiling will not drive nearly the amount of air out needed to create that much vacuum. If you believe that, you're ridiculous. You can test yourself. Put a pot of water on a stove, heat it to below boiling or steaming. See how much air you can drive out.
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Doougin
Member
- Jul 4, 2011
- 80
- 0
- 66
At this point, I'm not sure if you are just a very dedicated idiot or trolling. Your statements that somebody must describe the process by which the heat pipes are created in order for you to accept that they do indeed include a liquid are ridiculous. You are also, completely out of hand and without any evidence to back up your claims, dismissing possibilities brought up in attempts to answer your completely irrelevant question.
However I am sure you will persist, so here is how these things actually work. A few minutes on Wikipedia do wonders.
According to Wikipedia, pressure really has nothing to do with heat pipes. All that matters is that all the liquids inside condense at the same temperature. To this end the liquid just needs to be boiled inside of the heat pipe, which drives out other gases.
PheonixEnigma has already explained this, nicely, but you ignored him, so hopefully this time you actually take note of this.
Hollow, enclosed copper tubes are an absolutely horrible way to transfer heat. Most insulators work by trapping large amounts of air with relatively little material. For evidence of this, I would direct you towards Aerogel. Air is simply horrible at transferring heat.
As you failed to even read a short Wikipedia entry about the very topic you are so willing to argue at length, I'll go ahead and source that for you here and here. As you will note, paper at 25C is about as thermally conductive as air at 400C.
It is simply ridiculous to contend that all of the heatsink manufacturers are ignoring basic physics in order to claim "we have (fake) heat pipes too!" while they proceed to save a tiny bit of copper (or just about any material better capable of transferring heat than air - for ideas look at the link above). In the mean time they would have roughly equal performance when they would easily be capable of delivering an incredible performance boost for relatively little additional cost, which would allow them to charge quite a bit for their much better product. Oh, and they are doing all of this while continually providing performance increases with each new generation of coolers.
monkeydelmagico
Diamond Member
- Nov 16, 2011
- 3,961
- 145
- 106
Would it help keep my brain cool? It's hard work disproving science and replacing fact with complicated conspiracy.
Funny, I was thinking an science channel episode of "how it's made" would be illustrative and enlightening to a lay-person like me.
Seriously though, thanks to OP and a few really smart and patient folks for putting out some excellent info. I learned/re-learned alot.
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easily testable hypothesis...record your temps with a retail heatpipe heatsink...then pierce all the pipes and test again. If the temps are the same, then indeed there is nothing in the pipes. A good test for those of us with more money than science.
Cap off one end of a pipe.
Connect the other open end to a vacuum pump.
Pump out all the air.
Crimp the pipe just in front of the pump, thus sealing it off, preventing any air from getting back into the pipe.
This process was already even hinted at in a previous post (ie why is one end of the pipe crimped?) It's actually a fairly common process. It's even used in making those neon glass tube signs, which also only operate properly in a vacuum. The only difference with the glass tubes is you melt and seal the glass ends instead of crimping them, for hopefully obvious reasons.
The simple fact is, if heat pipe coolers didn't actually operate as heat pipes, they would perform significantly worse than standard heat sink coolers.
Heat dissipation, or thermal conductance, is a measure of the amount of heat that can be dissipated through a given material as a result of temperature gradients on opposite ends of the material. This conductance is calculated based on the materials thermal conductivity (k), cross sectional area(A), and length(L).
Conductance = k*A/L
So Conductance increases as k or A increases, and as L decreases.
So if we're talking about copper tubes vs a copper block, the area of the copper tubes is significantly less than a copper block, and the Length (by length I mean distance between thermal conducting material and the cooling fins) of those copper tubes is significantly greater than that of the copper block. So if they didn't operate as heat pipes, they would be next to worthless as a cpu cooler. The only way they can remotely compete with a regular heat sink is if their thermal conductivity (k) is significantly higher. The only way k can be significantly higher is if they are, in fact, fully functional heat pipes.
I wasn't trying to say that learning about the actual process by which they are made wouldn't help to answer the question definitively. Of course it would.
I was calling his insistence that the only way to convince him/prove him wrong was to show him possible processes by which they could potentially make the pipes with a liquid inside ridiculous. While the exact process would obviously show the existence of the liquid, it is not required to know the process in order to reasonably conclude they do contain a liquid. But he wasn't even asking for that - he was just challenging people to come up with ways it might be done, and then just responding to every idea with a "nah, wouldn't work."
QuantumPion
Diamond Member
- Jun 27, 2005
- 6,010
- 1
- 76
The heat pipe does not have to be at a vacuum nor does it require the temperature to exceed the boiling point to function. It's called evaporation. It's why you cool when you sweat. Only in the case of a heat pipe using water, the water vapor is condensed at the cool end of the pipe and returned via a wick to the hot end.
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It doesn't matter if it's 100f or 500f all you need is enough pressure to force the air out and once it's out it's out and more heat will not make a difference.Take an unopened can of soup and drop it in 200f degree water and see how fast you remove the contents
know of fence
Senior member
- May 28, 2009
- 555
- 2
- 71
The most difficult concept to grasp here IMHO is that of vapor pressure http://www.chem.purdue.edu/gchelp/liquids/vpress.html, which mostly depends on temperature. Basically everybody knows that changing pressure will change when water boils, but understanding why water also evaporates at normal temperature is the key to understanding how heat pipes work.
Regardless of which fluid you fill inside a heatpipe, cooling will always work as long as the pipe IS NOT completely filled with liquid or all liquid is gaseous. The Gas-Liquid state inside the pipe will always have a higher "vapor pressure" on the warmer end, it doesn't have to boil. Same principle as sweating.
Heat pipes utilize a completely different principle than refrigeration, and thus don't require pentane or any of those easily liquefiable gasses.
Vapor pressure is the reason why you will never have a perfect vacuum in a tube with a liquid, the "empty" space will always be filled with with vapor, based on whichever vapor pressure this liquid has at a particular temperature.
Regardless of which fluid you fill inside a heatpipe, cooling will always work as long as the pipe IS NOT completely filled with liquid or all liquid is gaseous. The Gas-Liquid state inside the pipe will always have a higher "vapor pressure" on the warmer end, it doesn't have to boil. Same principle as sweating.
Heat pipes utilize a completely different principle than refrigeration, and thus don't require pentane or any of those easily liquefiable gasses.
Vapor pressure is the reason why you will never have a perfect vacuum in a tube with a liquid, the "empty" space will always be filled with with vapor, based on whichever vapor pressure this liquid has at a particular temperature.
Zap
Elite Member
- Oct 13, 1999
- 22,377
- 2
- 81
The first thing I want to say is that heatpipes exist. Bicker all you want about definitions and whether or not some form of liquid is in there. The fact remains that they exist and they do what they purport to do.
Here's how you can tell if a metal rod is a heatpipe. (Yes you can do this with your CPU cooler.) Boil some water. Dip one end of the metal rod into the boiling water while holding the other end.
A) If the end you are holding becomes hot pretty much immediately, then it is a heatpipe.
B) A solid rod (even of copper) will not heat up immediately like that.
C) A tube (even sealed off on both ends and with either higher or lower pressure) that is not a heatpipe will not heat up like that.
Here's how you can tell if a metal rod is a heatpipe. (Yes you can do this with your CPU cooler.) Boil some water. Dip one end of the metal rod into the boiling water while holding the other end.
A) If the end you are holding becomes hot pretty much immediately, then it is a heatpipe.
B) A solid rod (even of copper) will not heat up immediately like that.
C) A tube (even sealed off on both ends and with either higher or lower pressure) that is not a heatpipe will not heat up like that.
OK, I need to clear a few things up: First of all I apologize to PhoenixEnigma. My intention was not to troll, but I admit I did not pay close enough attention to PhoenixEnigma's post. And I realize now that my earlier posts were biased. So, sorry.
Now let me address some misconceptions. 1st of all, let's look at what Visaoni said.
You said: ?According to Wikipedia, pressure really has nothing to do with heat pipes.?
Wikipedia says: ?At the hot interface within a heat pipe, which is typically at a very low pressure, a liquid in contact with a thermally conductive solid surface turns into a vapor.?
You said: ?It is simply ridiculous to contend that all of the heatsink manufacturers are ignoring basic physics in order to claim "we have (fake) heat pipes too!" while they proceed to save a tiny bit of copper.? This was not my contention. You put those words in my mouth. My contention was this: A heat pipe has a vacuum container. Wikipedia states: ?A typical heat pipe consists of a sealed pipe or tube... A vacuum pump is used to remove all air from the empty heat pipe? Therefore I asked anyone to tell me how the vacuum pump was applied in order to create the low pressure.
You said: "Hollow, enclosed copper tubes are an absolutely horrible way to transfer heat... Air is simply horrible at transferring heat.? I never implied that air was conducting the heat. What I implied was that the pipes on CPU heatsinks were not heat pipes. You can't automatically jump to the conclusion that I think the air is conducting the heat. What I really thought was that it was the copper that was conducting the heat, and the hollow pipes were a marketing gimmick.
Ok. Hopefully that clears up some misunderstanding. But let's forget that and move on because the crux of the argument has to be clearly defined. So let's focus upon the fundamental question, and that is this: Are the pipes on CPU heatsinks true ?heat pipes,? or is this a marketing gimmick?
To answer this question, I will examine the evidence.
Let's work from the beginning. The following long paragraph is how I will establish the logic behind concepts I will use later. You may skip over it if you want to get right to the ?heat pipe? part.
A computer processor generates heat from the current flowing through millions of transitors within the cpu, or the impedance of the circuits themselves (http://en.wikipedia.org/wiki/CPU_power_dissipation). Excessive heat can degrade the life of the circuits, or even cause the circuitry to malfunction. That is why the processor, like other high-wattage electronics, needs some way to dissipate, transfer, or otherwise release the heat. (http://en.wikipedia.org/wiki/Computer_cooling) There are a number of ways that computer manufacturers and users can prevent the CPU from overheating. Some are more expensive, impractical, or less efficient than others. Sure, you can cool a CPU with a closed loop of liquid nitrogen. But to set up such a system would cost a fortune and would be impractical for 99% of computer users. That is why certain technologies have become standard. The main standard is heat convection, or air-cooling (http://en.wikipedia.org/wiki/Convective_heat_transfer). Heat from the processor is first transferred to a heat-sink via conduction. The large surface area of the heatsink then allows a convective heat transfer to the air. Wikipedia notes: ?Although often referred to as a distinct process, convection includes the combined processes of both conduction and convective heat transfer.? Depending upon the manufacturer and design, the heat sink may or may not have a fan to move hot air out and cool air in. Most do, but there are exceptions (http://www.nofancomputer.com/eng/products/CR-100A.php). The vast majority of computer users rely upon heatsinks to cool the processor. Among the overclocking community there are some who use water cooling systems. Technically these setups use forced convection with water as the fluid. This water is moved through a loop and a radiator in order to maximize the results from incorporating a liquid. Much rarer but also utilized is vapor compression phase change cooling, which is commonly shortened to just ?phase change? cooling. Since this setup uses a vapor compressor to change the gas back into a liquid, this is not referred to as a ?latent? device. There are numerous examples on internet pages and forums who have used these phase change coolers (http://www.overclockers.com/build-your-own-phase-change-pc-cooling-system)
The afore-mentioned paragraph mentions the common and uncommon standards for cooling used in personal computing. Now we come to the cooling technology which is called a ?heat pipe.?
Just what, exactly, is a heat pipe? To answer this question, I refer to two well-known and referenced sources. I use two for redundancy and to control for the chance that there might be an error in either one.
The first source is Wikipedia. ?A heat pipe or heat pin is a heat-transfer device that combines the principles of both thermal conductivity and phase transition to efficiently manage the transfer of heat between two solid interfaces.? http://en.wikipedia.org/wiki/Heat_pipe#Heat_transfer
The second source is Thermacore: "Heat pipes are the most common passive, capillary-driven of the two-phase systems.? http://www.thermacore.com/thermal-basics/heat-pipe-technology.aspx
The two sources both agree that heat pipes use both thermal conduction and phase change cooling. These properties are universal, with no exception. However, there are a number of other components of heat pipes which are common, but not necessarily universal. This contradicts my previous post, but since I am attempting to be unbiased I will mention it. Wikipedia states that wicks are common, but not necessary ? gravity may also be used to return the cold liquid to the heat source. The Wikipedia article also mentions that heat pipes ?typically? operate under low vacuum. However, ?typically? does not mean that it CANNOT operate with no vacuum. Thermacore says that heat pipes contain vacuums ? however this is only in regards to the products they manufacture. Taking a look at the physics behind evaporate cooling, nothing leads me to believe that a setup without vacuum could not be created ? it would probably just be very ineffective and large in size.
So, according to the sources, a true heat pipe must have heat conduction AND two-phase cooling. Let's look at number one: Heat conduction. To test this, all you have to do is place your finger on the pipes of the heatsink. If they warm up as the processor operates, and cool down when it is shut off, then they are conducting heat. I tested this, and it's true. So I know that CPU heatsinks do in fact conduct heat. Referring back to my concepts paragraph, we know that conducting heat to the fins of the heatsink is what allows the heat to effectively convect into the air around it.
That clears up part #1 of the definition to my satisfaction. But notice that our sources say in order to be a true heat pipe, they must also transfer heat by two-phase cooling. Does a CPU heatsink do this? Let's look at the evidence.
In order to utilize the physics behind phase change cooling, a real heat pipe would have to contain liquid. The principle behind phase-change cooling is called the enthalpy of vaporization. This is essentially the energy transfer it takes to change a liquid to a gas. http://en.wikipedia.org/wiki/Enthalpy_of_vaporization Doing this has a cooling effect. http://en.wikipedia.org/wiki/Evaporative_cooler#Physical_principles
For phase change cooling to occur, liquid must be present within a heat pipe. Thus a test to see if a common CPU heatsink ?heat pipe? contains liquid would suggest it is. Although I have not tested this myself, there are a number of first-hand accounts available on the internet of opening up heatsink pipes. I've provided three sources here:
PhoenixEnigma provides one in the post above.
Here is another one: http://www.frostytech.com/articleview.cfm?articleID=2616
Another one: http://www.pcstats.com/articleview.cfm?articleid=2466
All three sources state that no liquid, or even moisture, was noticeable or present upon opening the pipes.
#1: ?You'll also notice there's nothing dripping out of it.?
#2: No mention of liquid or moisture ? from a professional review of a ?heat pipe.?
#3: ?The few times we have dissected a heatpipe here at Frostytech this is the kind of metal wick structure we discovered.? OK, the wick is there. Where's the liquid? ?In a freshly cracked open heatpipe the wick would be slightly wet.? Would be, not is. It should be moist, but I don't see the moisture.
Hmmm. This isn't looking too good for the heatsink makers. However, let's be fair. Just because it was not present does not necessarily indicate it does not exist in all so-called CPU ?heat pipes.? It simply means that the presence of liquid in a CPU ?heat pipe? has not been positively proven.
Further investigation into this matter reveals something else, also of interest to the inquiry. While CPU heatsink manufacturers clearly advertise their product as having ?heat pipes,? no where in the specs or facts of the product do they make mention of ?liquid,? ?coolant,? or otherwise. This seems to be an odd omission, contradictory to high-tech manufacturers such as Thermacore, who clearly state the working liquids (and vacuums) of the heat pipes they offer (http://www.thermacore.com/products/remote-dissipation.aspx mentions the coolants by name). This leads me to wonder, if the CPU heatsinks with the so-called ?heat pipes? contain a liquid, why is no mention made of this on the manufacturers websites? I have specifically checked numerous websites of CPU heatsink manufacturers who advertise their products as having ?heat pipes? to verify what liquid or coolant used. None of these advertise, or even make mention, of any such liquid:
- Official spec sheet for Thermolab BADA with ?heat-pipe? coolers: http://thermolab.co.kr/product_eng/8494
- Spec sheet for Zalman CNPS10x with heat pipes: http://www.zalman.co.kr/ENG/product/Product_Read.asp?idx=378
- Noctua NH-D14 with six ?heat pipes?:http://noctua.at/main.php?show=productview&products_id=34&lng=en
- Thermaltake V1 CL-P0401 with ?heat pipes?: http://www.thermaltakeusa.com/Product.aspx?C=1148&ID=1548#Tab0
- Here's a ?heat pipe? HDD cooler: http://www.zalman.co.kr/eng/product/Product_Read.asp?idx=134
What does all this tell me? The conclusion of my investigation is that CPU heatsink manufacturers claim that their heatsink pipes are ?heat pipes,? however no evidence I found has proved this claim. The evidence, in fact, strongly suggests that CPU heatsink pipes contain no liquid, and hence are not true ?heat pipes.? My belief is that CPU heatsink manufacturers use the term ?heat pipe? as a marketing gimmick, mainly. Do I think they are deliberately or maliciously lying about their product to bilk unsuspecting people? No. Would I put it beyond some of these companies to manufacture a heatsink pipe with a capillary surface and call it a ?heat pipe?? Well, China does have a fake Apple store, alot of these coolers are manufactured in Asia, so... You can draw your own conclusions.
Mainly, I think they do not fully understand the distinctions around the technology that true heat pipe manufacturers make. For this reason, I believe that there is a misconception around the term ?heat pipe.? Hopefully this post will go some way to clearing things up. This is what I found and believe. However, if someone else has better proof or evidence to suggest otherwise, I am more than willing to listen.
Now let me address some misconceptions. 1st of all, let's look at what Visaoni said.
You said: ?According to Wikipedia, pressure really has nothing to do with heat pipes.?
Wikipedia says: ?At the hot interface within a heat pipe, which is typically at a very low pressure, a liquid in contact with a thermally conductive solid surface turns into a vapor.?
You said: ?It is simply ridiculous to contend that all of the heatsink manufacturers are ignoring basic physics in order to claim "we have (fake) heat pipes too!" while they proceed to save a tiny bit of copper.? This was not my contention. You put those words in my mouth. My contention was this: A heat pipe has a vacuum container. Wikipedia states: ?A typical heat pipe consists of a sealed pipe or tube... A vacuum pump is used to remove all air from the empty heat pipe? Therefore I asked anyone to tell me how the vacuum pump was applied in order to create the low pressure.
You said: "Hollow, enclosed copper tubes are an absolutely horrible way to transfer heat... Air is simply horrible at transferring heat.? I never implied that air was conducting the heat. What I implied was that the pipes on CPU heatsinks were not heat pipes. You can't automatically jump to the conclusion that I think the air is conducting the heat. What I really thought was that it was the copper that was conducting the heat, and the hollow pipes were a marketing gimmick.
Ok. Hopefully that clears up some misunderstanding. But let's forget that and move on because the crux of the argument has to be clearly defined. So let's focus upon the fundamental question, and that is this: Are the pipes on CPU heatsinks true ?heat pipes,? or is this a marketing gimmick?
To answer this question, I will examine the evidence.
Let's work from the beginning. The following long paragraph is how I will establish the logic behind concepts I will use later. You may skip over it if you want to get right to the ?heat pipe? part.
A computer processor generates heat from the current flowing through millions of transitors within the cpu, or the impedance of the circuits themselves (http://en.wikipedia.org/wiki/CPU_power_dissipation). Excessive heat can degrade the life of the circuits, or even cause the circuitry to malfunction. That is why the processor, like other high-wattage electronics, needs some way to dissipate, transfer, or otherwise release the heat. (http://en.wikipedia.org/wiki/Computer_cooling) There are a number of ways that computer manufacturers and users can prevent the CPU from overheating. Some are more expensive, impractical, or less efficient than others. Sure, you can cool a CPU with a closed loop of liquid nitrogen. But to set up such a system would cost a fortune and would be impractical for 99% of computer users. That is why certain technologies have become standard. The main standard is heat convection, or air-cooling (http://en.wikipedia.org/wiki/Convective_heat_transfer). Heat from the processor is first transferred to a heat-sink via conduction. The large surface area of the heatsink then allows a convective heat transfer to the air. Wikipedia notes: ?Although often referred to as a distinct process, convection includes the combined processes of both conduction and convective heat transfer.? Depending upon the manufacturer and design, the heat sink may or may not have a fan to move hot air out and cool air in. Most do, but there are exceptions (http://www.nofancomputer.com/eng/products/CR-100A.php). The vast majority of computer users rely upon heatsinks to cool the processor. Among the overclocking community there are some who use water cooling systems. Technically these setups use forced convection with water as the fluid. This water is moved through a loop and a radiator in order to maximize the results from incorporating a liquid. Much rarer but also utilized is vapor compression phase change cooling, which is commonly shortened to just ?phase change? cooling. Since this setup uses a vapor compressor to change the gas back into a liquid, this is not referred to as a ?latent? device. There are numerous examples on internet pages and forums who have used these phase change coolers (http://www.overclockers.com/build-your-own-phase-change-pc-cooling-system)
The afore-mentioned paragraph mentions the common and uncommon standards for cooling used in personal computing. Now we come to the cooling technology which is called a ?heat pipe.?
Just what, exactly, is a heat pipe? To answer this question, I refer to two well-known and referenced sources. I use two for redundancy and to control for the chance that there might be an error in either one.
The first source is Wikipedia. ?A heat pipe or heat pin is a heat-transfer device that combines the principles of both thermal conductivity and phase transition to efficiently manage the transfer of heat between two solid interfaces.? http://en.wikipedia.org/wiki/Heat_pipe#Heat_transfer
The second source is Thermacore: "Heat pipes are the most common passive, capillary-driven of the two-phase systems.? http://www.thermacore.com/thermal-basics/heat-pipe-technology.aspx
The two sources both agree that heat pipes use both thermal conduction and phase change cooling. These properties are universal, with no exception. However, there are a number of other components of heat pipes which are common, but not necessarily universal. This contradicts my previous post, but since I am attempting to be unbiased I will mention it. Wikipedia states that wicks are common, but not necessary ? gravity may also be used to return the cold liquid to the heat source. The Wikipedia article also mentions that heat pipes ?typically? operate under low vacuum. However, ?typically? does not mean that it CANNOT operate with no vacuum. Thermacore says that heat pipes contain vacuums ? however this is only in regards to the products they manufacture. Taking a look at the physics behind evaporate cooling, nothing leads me to believe that a setup without vacuum could not be created ? it would probably just be very ineffective and large in size.
So, according to the sources, a true heat pipe must have heat conduction AND two-phase cooling. Let's look at number one: Heat conduction. To test this, all you have to do is place your finger on the pipes of the heatsink. If they warm up as the processor operates, and cool down when it is shut off, then they are conducting heat. I tested this, and it's true. So I know that CPU heatsinks do in fact conduct heat. Referring back to my concepts paragraph, we know that conducting heat to the fins of the heatsink is what allows the heat to effectively convect into the air around it.
That clears up part #1 of the definition to my satisfaction. But notice that our sources say in order to be a true heat pipe, they must also transfer heat by two-phase cooling. Does a CPU heatsink do this? Let's look at the evidence.
In order to utilize the physics behind phase change cooling, a real heat pipe would have to contain liquid. The principle behind phase-change cooling is called the enthalpy of vaporization. This is essentially the energy transfer it takes to change a liquid to a gas. http://en.wikipedia.org/wiki/Enthalpy_of_vaporization Doing this has a cooling effect. http://en.wikipedia.org/wiki/Evaporative_cooler#Physical_principles
For phase change cooling to occur, liquid must be present within a heat pipe. Thus a test to see if a common CPU heatsink ?heat pipe? contains liquid would suggest it is. Although I have not tested this myself, there are a number of first-hand accounts available on the internet of opening up heatsink pipes. I've provided three sources here:
PhoenixEnigma provides one in the post above.
Here is another one: http://www.frostytech.com/articleview.cfm?articleID=2616
Another one: http://www.pcstats.com/articleview.cfm?articleid=2466
All three sources state that no liquid, or even moisture, was noticeable or present upon opening the pipes.
#1: ?You'll also notice there's nothing dripping out of it.?
#2: No mention of liquid or moisture ? from a professional review of a ?heat pipe.?
#3: ?The few times we have dissected a heatpipe here at Frostytech this is the kind of metal wick structure we discovered.? OK, the wick is there. Where's the liquid? ?In a freshly cracked open heatpipe the wick would be slightly wet.? Would be, not is. It should be moist, but I don't see the moisture.
Hmmm. This isn't looking too good for the heatsink makers. However, let's be fair. Just because it was not present does not necessarily indicate it does not exist in all so-called CPU ?heat pipes.? It simply means that the presence of liquid in a CPU ?heat pipe? has not been positively proven.
Further investigation into this matter reveals something else, also of interest to the inquiry. While CPU heatsink manufacturers clearly advertise their product as having ?heat pipes,? no where in the specs or facts of the product do they make mention of ?liquid,? ?coolant,? or otherwise. This seems to be an odd omission, contradictory to high-tech manufacturers such as Thermacore, who clearly state the working liquids (and vacuums) of the heat pipes they offer (http://www.thermacore.com/products/remote-dissipation.aspx mentions the coolants by name). This leads me to wonder, if the CPU heatsinks with the so-called ?heat pipes? contain a liquid, why is no mention made of this on the manufacturers websites? I have specifically checked numerous websites of CPU heatsink manufacturers who advertise their products as having ?heat pipes? to verify what liquid or coolant used. None of these advertise, or even make mention, of any such liquid:
- Official spec sheet for Thermolab BADA with ?heat-pipe? coolers: http://thermolab.co.kr/product_eng/8494
- Spec sheet for Zalman CNPS10x with heat pipes: http://www.zalman.co.kr/ENG/product/Product_Read.asp?idx=378
- Noctua NH-D14 with six ?heat pipes?:http://noctua.at/main.php?show=productview&products_id=34&lng=en
- Thermaltake V1 CL-P0401 with ?heat pipes?: http://www.thermaltakeusa.com/Product.aspx?C=1148&ID=1548#Tab0
- Here's a ?heat pipe? HDD cooler: http://www.zalman.co.kr/eng/product/Product_Read.asp?idx=134
What does all this tell me? The conclusion of my investigation is that CPU heatsink manufacturers claim that their heatsink pipes are ?heat pipes,? however no evidence I found has proved this claim. The evidence, in fact, strongly suggests that CPU heatsink pipes contain no liquid, and hence are not true ?heat pipes.? My belief is that CPU heatsink manufacturers use the term ?heat pipe? as a marketing gimmick, mainly. Do I think they are deliberately or maliciously lying about their product to bilk unsuspecting people? No. Would I put it beyond some of these companies to manufacture a heatsink pipe with a capillary surface and call it a ?heat pipe?? Well, China does have a fake Apple store, alot of these coolers are manufactured in Asia, so... You can draw your own conclusions.
Mainly, I think they do not fully understand the distinctions around the technology that true heat pipe manufacturers make. For this reason, I believe that there is a misconception around the term ?heat pipe.? Hopefully this post will go some way to clearing things up. This is what I found and believe. However, if someone else has better proof or evidence to suggest otherwise, I am more than willing to listen.
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Neither of the articles you cite from Frosty Tech or PC Stats say anything about whether there was actually any fluid in the pipe when they opened it. Both are about the structure of the wick inside the pipes and both say there will be a fluid in the pipes prior to opening. The statement "The few times we have dissected a heatpipe here at Frostytech this is the kind of metal wick structure we discovered. In a freshly cracked open heatpipe the wick would be slightly wet" from the latter article in fact implies that they do find fluid in pipes they open. Your sources don't even say what you think they do. All you've clarified is that your posts are straight-up FUD.
Well, that's not entirely accurate. The Frostytech reviewer did not note or mention finding any liquid. Since he was reviewing a "heat pipe" which works using two-phase cooling, the omission of the working fluid used would be a significant error.
Again, my original statement remains true, which is: no positive proof of two-phase cooling is shown in any of the 3 sources mentioned.
PhoenixEnigma
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- Aug 6, 2011
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FWIW, I emailed a couple heatsink manufactures to see what they would say. CoolerMaster is the only one to reply so far. Per "Jarad", all of the heatpipes used in their heatsinks use pure water as a working fluid. The 212 line might be good, but it's not that good - if they're using real heatpipes, it's pretty clear everyone is.
You can either take their word for it, along with the heaps of evidence that's been presented here, or you can keep wearing your tinfoil hat.
At this point, you're trying to argue that the entire CPU heatsink industry is actively lying to consumers, including manufacturing objects that exactly match authentic heatsinks in every way except the presence of a fluid inside, to the detriment of heatsink performance. That's a pretty substantial claim, and I think it's fair to place the burden of proof on you. Do you have any evidence to back up your claims, bearing in mind that absence of evidence is not evidence of absence?
Unless you have something else, something new and verifiable, I'm done here. I've got other brick walls to beat my head against.
You can either take their word for it, along with the heaps of evidence that's been presented here, or you can keep wearing your tinfoil hat.
At this point, you're trying to argue that the entire CPU heatsink industry is actively lying to consumers, including manufacturing objects that exactly match authentic heatsinks in every way except the presence of a fluid inside, to the detriment of heatsink performance. That's a pretty substantial claim, and I think it's fair to place the burden of proof on you. Do you have any evidence to back up your claims, bearing in mind that absence of evidence is not evidence of absence?
Unless you have something else, something new and verifiable, I'm done here. I've got other brick walls to beat my head against.
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